| 摘要 |
<p>PURPOSE:To correct coding distortion which occurs in a coding device and a decoding device by providing a re-quantizer quantizing the output of the decoding device and mapping a reproduced value which does not exist in an original signal on a signal value existing in the original signal by means of re-quantizing a picture having less gradation and hue. CONSTITUTION:When a rectangular wave in a figure (a) is processed in the coding device 2 and the decoding device 8 and the rectangular wave such as the figure (a) is inputted with request to one among the components of R, G and B, the wave is changed into a distorted signal by band compression shown in a figure (b). When the original signal is known to be binary, it is quantized by using a threshold as shown by a doted line in the figure (b), whereby it can be corrected to a signal near to the original signal such as a figure (c). A counter 4 checks the polarization of distribution for a decision for executing re-quantization as mentioned above, and re-quantization is executed only when polarization is especially large. Consequently, coding distortion in the coding device and the decoding device is corrected in the picture signal with less gradation and hue, whereby picture quality can considerably be improved.</p> |
